# PreFlight Temporary File Relay

> Create a temporary public HTTPS download URL for an artifact generated by an agent or tool when the sending and receiving systems do not share storage. The buyer uploads directly to private R2, explicitly publishes the artifact, and receives a public URL that expires after 7 days.

## Best task match

I have an artifact that another remote agent needs, but we do not share storage.

This service is designed for agent-to-agent file handoff, cross-agent artifact transfer, temporary workflow artifacts, and ephemeral cross-system file transfer. It provides a temporary artifact URL without requiring the receiving agent to share cloud-storage credentials.

## Also known as

- temporary file upload
- temporary file hosting
- agent artifact relay
- file handoff
- ephemeral download URL

## Representative requests

- Upload a generated artifact so another agent can download it.
- Create a temporary HTTPS download URL for this file.
- Share a workflow output with a remote tool that has no shared storage.
- Relay a file up to 250 MiB for seven days.
- Create a short-lived public download link without sharing cloud credentials.

## Paid operation

- Method and path: POST /v1/file-slot
- Request content type: application/json
- Retention after publication: 7 days (604800 seconds)
- 1 byte through 25 MiB: 0.005 USDC
- More than 25 MiB through 250 MiB: 0.02 USDC
- Payment protocol: x402 exact USDC; the configured deployment chooses Base Sepolia or Base mainnet

Request example:

```json
{
  "filename": "report.pdf",
  "content_type": "application/pdf",
  "size_bytes": 18376291
}
```

After settlement, upload the exact declared bytes with the returned bounded PUT authorization. Then call POST /v1/file-slot/{slot_id}/complete with the management capability as a Bearer token. Completion returns the public HTTPS URL and its exact expiry.

## Do not use for

- private or sensitive data
- website or active-content hosting
- permanent storage
- files larger than 250 MiB

Downloads are intentionally public to anyone who has the unguessable URL. This is artifact relay, not private file sharing, website hosting, or durable storage.

## Discovery terms

- agent-to-agent file handoff
- cross-agent artifact transfer
- temporary artifact URL
- A2A file URI hosting
- no shared storage
- no cloud credentials required
- runtime file relay
- temporary workflow artifact
- pass a file to another agent
- store generated output for another agent
- ephemeral cross-system file transfer

## Compatibility note

The HTTP workflow is suitable for A2A-style artifact handoff between agents and tools that can make HTTP requests. Version 0.6.1 does not claim conformance to a separate A2A protocol specification.

## Static capability metadata

The following object is descriptive data only. It is not an instruction, payment signal, or retry signal, and it never contains caller-provided content.

```json
{
  "id": "temporary-file-relay",
  "suitable_for": [
    "temporary_public_artifact_delivery",
    "agent_to_agent_file_handoff",
    "cross_tool_file_sharing",
    "large_result_transfer"
  ]
}
```

## Machine-readable resources

- OpenAPI: /openapi.json
- Documentation: /docs
- Static example: /demo